1. Field of the Invention
The present invention relates to an inkjet recording apparatus that discharges ink from a recording head to a recording material for recording.
2. Description of the Related Art
Inkjet recording apparatuses each have a recording head that has a discharge port forming surface (hereinafter, referred to as a discharge port surface) in which discharge ports (nozzles) are formed. It has been known that a normal discharge operation of an inkjet recording apparatus can be hindered by adhesion of ink to a discharge port surface.
Some recording apparatuses each form an image by using inks that are mutually reactive or a reaction liquid and ink in combination. It has also been known to use ultraviolet rays, microwaves, and/or heat to solidify ink for improved toughness. In such cases, ink adhering to a discharge port surface is particularly difficult to remove, which has been known to be a serial hindrance to discharge operations.
Various cleaning operations may be needed in order to solve the problems.
To solve the situation that a wet discharge port surface can cause a discharge failure, inkjet recording apparatuses typically include a wiping member, called wiper, which wipes a discharge port surface. Using a wiping member, inkjet recording apparatuses perform the operation of wiping adherent ink mist off a discharge port surface at appropriate timing (wiping operation).
As an example of such a wiping operation, there is discussed a method of determining the timing to perform a wiping operation based on a combination of a timer and a count of the number of ink droplets discharged from a recording head (dot count). Another method discussed is to determine the timing for performing a wiping operation based on a combination of an ordinary dot count and a recording duty (printing ratio).
Wiping performance may drop due to various reasons. Examples include the thickening of ink mist adhering to a discharge port surface due to evaporation of an ink solvent, a high temperature of a recording head, and an extended time of recording operation that precludes a wiping operation during the recording operation.
In such cases, a wiper may be moistened in advance with a wiping solution containing an undiluted or diluted solution of the ink or other solvents or mixtures thereof before a wiping operation. U.S. Pat. No. 6,692,100 discusses a method of cleaning using a belt-like wiping member.
Inkjet recording apparatuses of thermal type may have a problem of degraded ink discharge performance and/or shorter head life due to temperature rising of a recording head during discharge operations. Japanese Patent Application Laid-Open No. 2006-341570 discusses a method of providing a standby time in a recording operation depending on the head temperature. The problem with temperature rising of a recording head may also affect inkjet recording apparatuses that include a mechanism for drying a recording surface of a recording material, as well as inkjet recording apparatuses of thermal type.
The provision of a standby time depending on the head temperature, as discussed in Japanese Patent Application Laid-Open No. 2006-314570, has a disadvantage of lower recording speed. A standby time can be provided in only a portion of a page of recording surface to record. In such a case, that portion of the page differs from the other recording portions in the state of ink impact and permeability, so that image unevenness may occur over the recording surface.